**Please Note: The CO2Meter offices will be closed for the Memorial Day Holiday beginning at 5:00PM EDT Friday, May 27, 2022. All operations will reopen Tuesday, May 31 at 8:30AM EDT. Orders placed after 11:00 am et. May 27 will be fulfilled on Tuesday, May 31.**


CO2 Sensor Range: PPM and Percentage Compared

Understanding carbon dioxide ppm range

One of the most common questions we receive at CO2Meter.com, is "What CO2 monitoring device, is best for my industry?". And, depending on your use case, environment, and use of gas - will typically determine which gas detection device will suit your needs. 

However, what many individuals fail to realize is that carbon dioxide monitors are offered in quite a variety of ranges, from 1,000ppm (parts per million) all the way to 100% CO2. Selecting the sensor or monitor with the correct range of CO2 is also extremely important. This is because the narrower the range of CO2 levels measured, the more accurate the sensor or device will be.

For example, a 200ppm change will be seen on a 1,000ppm CO2 sensor, but not on a 100% CO2 sensor.

Determine your need for CO2 Monitoring

As many of us know, carbon dioxide (CO2) can be found and used in numerous ways across our environment. From releasing CO2 gas through exhalation, given off during combustion, or cycled through during the process of photosynthesis - carbon dioxide (CO2) plays such an important role if you think about it. 

However, what makes a true need for carbon dioxide monitoring is when in many cases the gas becomes hazardous, creates negative impact to ones health, or is needed to be further analyzed for research purposes.

Even though carbon dioxide is colorless, odorless, and tasteless it can be measured using specific sensing technologies, most commonly deferred to as non-dispersive infrared sensing. These CO2 sensors allow the invisible gas to be analyzed by measuring the amount of light that passes through an optical filter. The carbon dioxide gas is measured by the difference between the amount of light radiated by the IR lamp and the amount of IR light received by the detector is measured.

What should a CO2 Sensor Read?

When it comes to what makes up a quality carbon dioxide (CO2) sensor, it is based on the sensor technology at the core of the sensor. At CO2Meter, our sensors incorporate best-in-class non-dispersive infrared technologies, otherwise known as "NDIR".

A CO2 sensor will use this NDIR technology to measure CO2 in air based on the absorption of infrared IR light at any given wavelength. Once the air enters the NDIR CO2 sensor it activates a light set at a specific wavelength which is able to measure the appropriate CO2 levels. Once the light is activated any CO2 inside the sensor will be recorded.

Understand Parts-per-million (PPM) vs. Percent CO2

In general, CO2 sensors and measurement devices can be divided into 3 groups:

  • 0 - 10,000ppm for indoor air quality (IAQ)
  • 5,000ppm - 5% for personal safety, restaurants, beverage, indoor agriculture, and life sciences
  • 5% - 100% for industrial, fire suppression testing, biological

Selecting the proper CO2 range for your application makes it easier to choose from our list of available CO2 sensors and products. It also ensures you'll have the most accurate sensor for your application.

But first it's important to know the difference between parts-per-million and % CO2.

Carbon dioxide is considered a trace gas in the atmosphere.

Suppose you had a box of dry, outdoor air with 1 million molecules of gas in it. If you could count and separate each of the molecules by hand, here are the piles you'd make:

Gas Percent in Fresh Air
  • 780,840 molecules of nitrogen (78.08%)
  • 209,460 molecules of oxygen (20.9%)
  • 93,400 molecules of argon (0.93%)
  • 500 molecules of hydrogen, helium, methane, others
  • 400 molecules of carbon dioxide

As you can see, once you get past counting the number of nitrogen, oxygen and argon molecules, the number of  molecules of the remaining gases in our theoretical box of air is very small.

For this reason gases with over 1% by volume are measured as a percent. For smaller volumes, sensor manufacturers and the gas industry measure CO2 and other trace gases in parts per million. For example, 0.04% CO2 is equal to 400 parts per million, which is commonly abbreviated as "400 ppm".

Choose your CO2 Sensor based on Industry 

Indoor Air Quality - 10,000ppm CO2

Indoor Air Quality Applications

When talking about indoor air, parts-per-million makes sense. Only in rare instances like being in a cave or near an active volcano would you ever be exposed to CO2 levels above 1% (10,000ppm) in nature.

That's why for indoor air quality (IAQ) in homes, schools, or office applications, a 2,000ppm to 10,000ppm CO2 sensor or monitor is the right choice. Fresh air contains approximately 400ppm CO2. The ASHRAE Standard for ambient indoor air in occupied spaces has changed over the years but in general they recommend between 800-1,000 ppm. 

Therefore, an indoor air quality monitor or sensor that measures at these levels and can indicate to individuals should the threshold exceed the standard; will be the most accurate for indoor air quality applications.

The most popular sensors we sell in this range are the K30 CO2 Sensor by Senseair and the COZIR Ambient CO2 sensor. These sensors are used worldwide by OEM manufacturers of indoor air quality devices. They are also used in outdoor air quality devices to monitor CO2 levels.

One of our popular desktop indoor air  quality monitors is the IAQ-MAX CO2 Monitor and Data Logger.

A 10,000ppm CO2 sensor is also a good choice for air quality verification in car parks or garages that must meet OSHA specifications. The Occupational Safety and Health Administration guidelines require that the time-weighted average (TWA) over an 8-hour workday for a garage employee should not exceed 5,000ppm.

Personal Safety - 5% CO2

CO2Meter Beverage Product Portfolio

For CO2 safety applications where workers or the public are around tanks or cylinders of stored carbon dioxide, a 5% CO2 sensor or device is the best choice. A CO2 leak in an enclosed area can be fatal. If a CO2 tank or cylinder leaks, these sensors can be used to set off an alarm. 5% CO2 sensors and devices meet all OSHA, NIOSH, NFPA, IFC, and NBIC Requirements.

co2 safety monitor

For example, the COZIR GC-0015 0-5% CO2 sensor would be a good sensor for an OEM safety device around stored CO2. For a wall mounted safety monitor customers choose the Remote CO2 Storage Safety 3 Alarm. For a hand-held portable device, these personal CO2 alarms use a 5% CO2 sensor.

These devices can all be used in applications such as restaurants, fast-food establishments, breweries, wineries, or cultivation facilities who are looking to ensure compliance and meet personal safety CO2 monitoring regulations per their jurisdiction. 

Industrial and Biological Processes - 100% CO2

 Industrial CO2Meter Products

For industrial and biological processes like wood gasification or biological incubators where high levels of CO2 are required, a 10-100% CO2 sensor or device is a good solution. For example, our SenseAir K33 ICB or COZIR Wide-Range 20% sensors are in this range. In addition, the high-speed CM-1000 Multi Sampling Data Logger is an excellent choice for incubation or industrial scientific applications.

sampling data logger

For applications like controlled atmosphere storage for grains that require the ability to measure up to 100% CO2, we recommend the COZIR GC-0016 and SprintIR GC-0018 CO2 sensors.

Another example is the MH-100 Biological Incubator CO2 Sensor. It is designed to monitor carbon dioxide levels in cell incubators to manage ideal cell and tissue growth, typically at 5%.

CO2 Monitoring Towards the Future

As the world evolves, so does the industries surrounding use, production, and storage of carbon dioxide. At CO2Meter, we are constantly keeping informed and educated on the numerous ways that you can use the gas across applications. 

Here are just a few more examples of use cases for carbon dioxide where monitoring is vital:

With all the different emerging applications compared to products we offer, it might seem confusing as to which one is best for your particular use. However, by understanding the proper CO2 range required, you can narrow down the list of sensors or products significantly in order to choose the right device for you.

Furthermore, for someone to become well-versed on CO2, it is also important to remain knowledgeable of current regulations, industry applications, signs of exposure, device use and analysis, and how to explain the dangers to others.

Of course, a CO2Meter specialist can always assist if you have any questions. Give us a call or contact us for more information.








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